Technical Abstract:
Farmers often plant monocultures or simple grass-legume mixtures in their pastures. Increased biodiversity in pastures may be one tool to improve sustainability and productivity. This fact sheet addresses some common questions regarding biodiversity in pastures. Very broadly, biodiversity refers to all of the biological material including the genetic material, species, and ecosystems that make up the natural world. Plant diversity is now recognized as a major influence on nutrient cycling and primary production. Having several plant species in a system fills niches, increases the chances of including a productive species, and if a stress occurs, a stress tolerant species can grow. For example, some plant species extract water and nutrients from different soil layers and some plant species can grow at different times of the year extending the grazing season. Our research shows: (i) Appropriate mixtures of many forage species can increase pasture forage yield, (ii) Increasing the number of species in a mixture can reduce weed invasion and insect pests, and (iii) Dairy cattle perform just as well on complex mixtures of forages and on monocultures or simple mixtures. Some management practices affect pasture biodiversity indirectly. For example, using rotational grazing and managing pastures to leave more stubble and forage residue can influence beneficial insect and soil microbe populations and benefit some wildlife species. The most direct way to affect pasture biodiversity is to plant and manage many different forages in pastures. There is no universal forage mixture or number of forage species that applies to all farms. The specific set of forages will depend on your goals, management, soil resources, weather, and many other factors. As a start, most producers should consider using grass-legume mixtures to reduce the cost and use of nitrogen fertilizer and improve the nutritive value of the pasture forage.